shift9k

I went to have my car tuned a few days ago, and a fueling issue came up. I have a walbro 255,id1000, with stock lines, rail, and fpr on pump gas. At 10psi I made 340/210, but over 8k rpm my afr shot up to 12 afr. So we shut it down on 10psi and 8k rpm redline to keep things safe. Now I know this pump is more than capable to supply enough fuel for my 400hp goal.
Could this be a fpr issue?
I do NOT have the pump run straight to the battery. Could it not be getting enough power?
Thanks for the advice in advance

1SlowSi

Running a relay does help keep the voltage consistent and could be your problem but you'll have to test that. A single Walbro, ID1000, and base pressure of 43-45 psi should max out around 430-450whp. With an inline Bosch 044, 600whp.

Kitesurfer s2000

As your boost goes up your fuel pressure goes up this means that the pump will struggle to keep pushing the fuel .

Rewire the pump to start with its very easy ,also make sure the fuel line connections on the pump itself are tight mine were lose.

If you have money to burn then put a full blown 340 in job sorted, there much much better pumps .

http://realstreetper...son-test-5.html

And read this :-) Lee.

riceball777

U just need to rewire the pump so it get power straight from the battery. A walbro 255 will support 600whp on gas and 475-500whp on e85 with stock fuel pressure.

Kitesurfer s2000

600whp rewired not with the 1000IDs I ran out at 450whp so rewired 500whp 600 is asking a lot .

herecomesboost

Are you running the factory base fuel pressure with your 1k's?

Irishflame27

Like mentioned before, do a fuel pump rewire to ensure constant consistent voltage, as a un modified walbro can support more than 500whp worth of flow. I have seen in some cases the fuel pump outlet hose inside the tank, the clamp is installed incorrectly causing a pressure drop as the pump bleeds pressure from the loose connection.

Kitesurfer s2000

^^^ This :-) mines stock fpr but at 18psi im outside the efficiency of my 340 pump .

C63AMG

How could you install the clamp incorrectly? It only goes on one way.

EDIT: Ah, I misread. The 2 clamps on the short piece of hose between the pump and the housing?

I had a very similar issue. Pressure dropping like a stone after 8k so a new pump was sent out to try. I am using a turbine driven 260lph pump (same idea as AEM, Aeromotive etc) which "should" be good for almost 600ish whp. It is directly wired to the battery with a relay and 20A fuse so there's no issue of current availability.

You mentioned the pressure increases as boost increases? I don't see the logic in that.

The car will use the fuel it's telling the pump to push (as boost increases more fuel is required). The flow will increase and the pressure, in theory, will maintain up to a certain flow rate. The pressure the pump can produce will decrease as the flow request increases. Most pumps have a flow vs pressure graph available showing this characteristic.

That's how I understand it anyway.

Kitesurfer s2000

Mine was lose as well put two clamps on the bugger.